Datasheet LTC5535 (Analog Devices) - 9
| Manufacturer | Analog Devices |
| Description | Precision 600MHz to 7GHz, RF Detector with Adjustable Gain and 12MHz Baseband Bandwidth |
| Pages / Page | 12 / 9 — APPLICATIO S I FOR ATIO. Operation. Output Amplifier. RF Detector. Demo … |
| File Format / Size | PDF / 243 Kb |
| Document Language | English |
APPLICATIO S I FOR ATIO. Operation. Output Amplifier. RF Detector. Demo Board Schematic
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LTC5535
U U W U APPLICATIO S I FOR ATIO Operation
The VOS input controls the DC input voltage to the output amplifier. V The LTC5535 RF detector integrates several functions to OS must be connected to ground if the DC output voltage is not to be changed. The output amplifier provide RF power detection over frequencies ranging is initially trimmed to 200mV (Gain = 2) with V from 600MHz to 7GHz. These functions include an internal OS con- nected to ground. frequency compensated output amplifier, an RF Schottky diode peak detector and a level shift amplifier to convert the The VOS pin is used to change the initial VOUT starting RF input signal to DC. The LTC5535 has both gain setting voltage. This function, in combination with gain adjust- and voltage offset adjustment capabilities. ment enables the LTC5535 output to span the input range of a variety of analog-to-digital converters. VOUT will not
Output Amplifier
change until VOS exceeds 200mV. The starting voltage at The output amplifier is capable of supplying typically VOUT for VOS >200mV is: 20mA into a load. The negative terminal VM is brought out VOUT = 0.5 • VOS • Gain to a pin for gain selection. External resistors connected where gain is the output amplifier gain. For a gain of 2, between VOUT and VM (RA) and VM to ground (RB) will set V the gain of this amplifier. OUT will exactly track VOS above 200mV. Gain = 1 + RA/RB
RF Detector
The amplifier is not unity gain stable; a minimum gain of The internal RF Schottky diode peak detector and level two is required. The output amplifier has a bandwidth of shift amplifier converts the RF input signal to a low 20MHz with a gain of 2. For increased gain applications, frequency signal. The detector demonstrates excellent the bandwidth is reduced according to the formula: efficiency and linearity over a wide range of input power. The Schottky diode is biased at about 50 Bandwidth = 40MHz/(Gain) = 40MHz • R µA and drives a B/(RA + RB) 5pF internal peak detector capacitor. For stable operation the gain setting resistors should be low values and the board capacitance on VM should be minimized. RB is recommended to be no greater than 500Ω for all gain settings.
Demo Board Schematic
VCC 2.7V TO 5.5V C1 C4 LTC5535ES6 0.1µF RF 39pF IN C2 1 6 RF 100pF IN VCC R1 2 5 GND VOUT (OPT) VOUT R2 3 4 RLOAD V 500Ω OS VM (OPT) 1% OFFSET R3 ADJUSTMENT 500Ω 1% GND 5535 DB 5535f 9
U U W U APPLICATIO S I FOR ATIO Operation
The VOS input controls the DC input voltage to the output amplifier. V The LTC5535 RF detector integrates several functions to OS must be connected to ground if the DC output voltage is not to be changed. The output amplifier provide RF power detection over frequencies ranging is initially trimmed to 200mV (Gain = 2) with V from 600MHz to 7GHz. These functions include an internal OS con- nected to ground. frequency compensated output amplifier, an RF Schottky diode peak detector and a level shift amplifier to convert the The VOS pin is used to change the initial VOUT starting RF input signal to DC. The LTC5535 has both gain setting voltage. This function, in combination with gain adjust- and voltage offset adjustment capabilities. ment enables the LTC5535 output to span the input range of a variety of analog-to-digital converters. VOUT will not
Output Amplifier
change until VOS exceeds 200mV. The starting voltage at The output amplifier is capable of supplying typically VOUT for VOS >200mV is: 20mA into a load. The negative terminal VM is brought out VOUT = 0.5 • VOS • Gain to a pin for gain selection. External resistors connected where gain is the output amplifier gain. For a gain of 2, between VOUT and VM (RA) and VM to ground (RB) will set V the gain of this amplifier. OUT will exactly track VOS above 200mV. Gain = 1 + RA/RB
RF Detector
The amplifier is not unity gain stable; a minimum gain of The internal RF Schottky diode peak detector and level two is required. The output amplifier has a bandwidth of shift amplifier converts the RF input signal to a low 20MHz with a gain of 2. For increased gain applications, frequency signal. The detector demonstrates excellent the bandwidth is reduced according to the formula: efficiency and linearity over a wide range of input power. The Schottky diode is biased at about 50 Bandwidth = 40MHz/(Gain) = 40MHz • R µA and drives a B/(RA + RB) 5pF internal peak detector capacitor. For stable operation the gain setting resistors should be low values and the board capacitance on VM should be minimized. RB is recommended to be no greater than 500Ω for all gain settings.
Demo Board Schematic
VCC 2.7V TO 5.5V C1 C4 LTC5535ES6 0.1µF RF 39pF IN C2 1 6 RF 100pF IN VCC R1 2 5 GND VOUT (OPT) VOUT R2 3 4 RLOAD V 500Ω OS VM (OPT) 1% OFFSET R3 ADJUSTMENT 500Ω 1% GND 5535 DB 5535f 9
